Analog-to-digital conversion device

ABSTRACT

An analog-to-digital conversion device is disclosed that independently executes each of events instructed by a host device. Each of analog-to-digital converters include an execution control unit, an event management unit that notifies of a synchronization instruction when a synchronous conversion event set up with a synchronous conversion operation is instructed as the event, and an operation control unit. When a particular one of the analog-to-digital converters receives the synchronization instruction and the execution control unit of the particular analog-to-digital converter is confirmed ready for the analog-to-digital conversion, the operation control unit in the particular analog-to-digital converter notifies the particular analog-to-digital converter is ready for the analog-to-digital conversion to the analog-to-digital converter other than the particular analog-to-digital converter, and instructs the execution control unit to execute the synchronous conversion event after a confirmation that all of the analog-to-digital converters are ready for the analog-to-digital conversion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/JP2016/085257, filed on Nov. 29, 2016, entitled“ANALOG-TO-DIGITAL CONVERSION DEVICE”, which claims priority based onthe Article 8 of Patent Cooperation Treaty, the entire contents of whichare incorporated herein by reference.

BACKGROUND

This disclosure relates to an analog-to-digital (AD) conversion devicethat performs AD conversion by converting analog signals into digitalsignals.

It is inefficient to provide an AD converter for each of many analogsignal inputs in a case of performing AD conversion by converting themany analog signals into digital signals. As such, Japanese PatentApplication Publication No. 2005-303575 (Patent Document 1) discloses aconfiguration to perform AD conversion by assigning one AD converter totwo or more analog signal inputs while selecting the analog signalinputs from one to another.

SUMMARY

One or more embodiments of analog-to-digital conversion device thatindependently executes each of events instructed by a host device mayinclude: at least two analog-to-digital converters that convert aninputted analog signal into a digital signal, wherein each of theanalog-to-digital converters independently executes an event instructedby the host device, wherein each of the analog-to-digital converters mayinclude: an execution control unit that controls execution of theanalog-to-digital conversion; an event management unit that notifies ofa synchronization instruction when a synchronous conversion event set upwith a synchronous conversion operation is instructed as the event; andan operation control unit that makes a notification to theanalog-to-digital converters, and instructs the execution control unitto execute the synchronous conversion event, wherein when a particularone of the analog-to-digital converters receives the synchronizationinstruction and the execution control unit of the particularanalog-to-digital converter is confirmed ready for the analog-to-digitalconversion, the operation control unit in the particularanalog-to-digital converter notifies the particular analog-to-digitalconverter is ready for the analog-to-digital conversion to theanalog-to-digital converter other than the particular analog-to-digitalconverter, and instructs the execution control unit to execute thesynchronous conversion event after a confirmation that all of theanalog-to-digital converters are ready for the analog-to-digitalconversion.

In one or more analog-to-digital conversion device, in a state where thesynchronization instruction is not notified due to a reason that theevent is not the synchronous conversion event, when the operationcontrol unit of the particular analog-to-digital converter confirms thatthe execution control unit of the particular analog-to-digital converteris ready for the analog-to-digital conversion, the operation controlunit may instruct the execution control unit to execute the eventwithout notifying the other analog-to-digital converter that theparticular analog-to-digital converter is ready for theanalog-to-digital conversion.

In one or more analog-to-digital conversion device, the synchronousconversion event may be set as a top priority among all of the events,and the event management unit may execute the synchronous conversionevent on a priority basis when events including the synchronousconversion event are in a standby state.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a circuit configuration of an ADconversion device according to one or more embodiments;

FIG. 2 is a view illustrating circuit configurations of AD convertersillustrated in FIG. 1 according to one or more embodiments;

FIG. 3 is a diagram illustrating an event correspondence table stored inan event management unit illustrated in FIG. 2;

FIG. 4 is a waveform diagram illustrating a synchronous conversionoperation by the AD conversion device according to one or moreembodiments; and

FIG. 5 is a diagram illustrating a circuit configuration of an ADconversion device according to one or more embodiments.

DETAILED DESCRIPTION

Embodiments are explained with reference to drawings. In the respectivedrawings referenced herein, the same constituents are designated by thesame reference numerals and duplicate explanation concerning the sameconstituents is basically omitted. All of the drawings are provided toillustrate the respective examples only. No dimensional proportions inthe drawings shall impose a restriction on one or more embodiments. Forthis reason, specific dimensions and the like should be interpreted withthe following descriptions taken into consideration. In addition, thedrawings may include parts whose dimensional relationship and ratios aredifferent from one drawing to another.

Referring to FIG. 1, an analog-to-digital (AD) conversion device 1according to one or more embodiments include: two AD converters (ADC) 11and 12 each of which converts an inputted analog signal into a digitalsignal; a selector (MPX) 21 that selects the analog signal to beinputted to the ADC 11; and a selector (MPX) 22 that selects the analogsignal to be inputted to the ADC 12. Moreover, the ADC 11 and 12 as wellas the MPX 21 and 22 are operated in accordance with sampling blocks ofa predetermined cycle (a sampling cycle).

Each of the ADC 11 and 12 performs AD conversion by converting an analogsignal that corresponds to an event designated by an event signal EVEinputted from a not-illustrated host device into a digital signal. Theevent signal EVE designates one of events that are set up withpriorities. Meanwhile, each event is set up with analog input or inputsto be subjected to the AD conversion by the ADC 11 and 12 out of analoginputs CH_0 to CH_n connected to the MPX 21 and 22. In this embodiment,the same analog inputs CH_0 to CH_n are assumed to be connected to theMPX 21 and 22 for the convenience of explanation. However, the analoginputs CH to be connected to the MPX 21 and the MPX 22 may be determinedseparately as desired.

Referring to FIG. 2, each of the ADC 11 and 12 includes an eventmanagement unit 31 that manages an operation of each event designated bythe event signal EVE, an operation control unit 32 that controls atiming to start the AD conversion, and an execution control unit 33 thatcontrols execution of the AD conversion.

An event correspondence table as illustrated in FIG. 3 is set to theevent management unit 31. Here, the priorities of the events (events “0”to “4”) to be designated by the event signal EVE, and the analog inputor inputs among the analog inputs CH_0 to CH_n connected to the MPX 21and 22 to be subjected to the AD conversion by the ADC 11 and 12 are setup in the event correspondence table. Here, in the event correspondencetable illustrated in FIG. 3, the event “0” is set as a top prioritywhere the analog input CH_0 is set to be subjected to the AD conversionby the ADC 11 while the analog input CH_1 is set to be subjected to theAD conversion by the ADC 12, respectively.

When the event signal EVE is inputted, the event management unit 31refers to the event correspondence table to determine whether or notthere is assignment of analog input or inputs CH to be subjected to theAD conversion, and outputs a trigger signal TRI to the operation controlunit 32.

The AD conversion device 1 is operated independently of the host device.Accordingly, the event signal EVE from the host device may be inputtedto the event management unit 31 even when another event is in execution,whereby two or more events may be put into a standby state. In thiscase, after the event in execution is completed, the event managementunit 31 subsequently causes the AD conversion device 1 to execute theevent with the top priority among the events in the standby state.Incidentally, the trigger signal TRI is a signal that notifies ofexistence of the event to be executed next. Accordingly, if one or moreevents are in the standby state and the event signal EVE is inputted,the trigger signal TRI is outputted after the event in execution iscompleted.

When the trigger signal TRI is inputted, the operation control unit 32outputs an entry signal ENT to the execution control unit 33. When theexecution control unit 33 gets ready for the AD conversion in responseto the entry signal ENT, the execution control unit 33 outputs a readysignal RED to the operation control unit 32. The entry signal ENT is asignal to request the execution control unit 33 to get ready forexecution of the AD conversion, and a state of output of the entrysignal ENT is maintained until the ready signal RED is inputted from theexecution control unit 33.

When the ready signal RED is inputted, the operation control unit 32outputs an execution signal EXE for instructing execution of the ADconversion to the event management unit 31 and to the execution controlunit 33. In response thereto, the event management unit 31 selects theanalog input or inputs by using a selection signal SEL while theexecution control unit 33 performs the AD conversion by converting theanalog signals from the analog inputs selected by the event managementunit 31 serially into digital signals. Here, when the event managementunit 31 selects the final analog input during the event in execution,the event management unit 31 outputs an end signal END to the operationcontrol unit 32 so as to cause the operation control unit 32 to stopoutputting the execution signal EXE.

The event “0” of the top priority is set to a synchronous conversionoperation in which converted values by the ADC 11 and the ADC 12 aresynchronized to the same hour. Here, each of the ADC 11 and 12 acquiresa value during execution of conversion processing by saving a voltageinto an inner capacitor and measuring the voltage in the capacitor. Forthis reason, in order to synchronize the converted values by the ADC 11and the ADC 12 to the same hour, it is only necessary to start savingthe voltages by the ADC 11 and the ADC 12 at the same hour. Hence, thesynchronous conversion operation is controlled such that the ADconversion by the ADC 11 and by the ADC 12 is started at the same hour.

Next, the synchronous conversion operation by the AD conversion device 1is described with reference to FIG. 4. In FIG. 4, line (a) indicates asynchronization instruction signal SYNC outputted from the eventmanagement unit 31 of each of the ADC 11 and the ADC 12, line (b)indicates a trigger signal TRI_1 outputted from the event managementunit 31 of the ADC 11, line (c) indicates an entry signal ENT_1outputted from the operation control unit 32 of the ADC 11, line (d)indicates a synchronized output signal SYNCOUT_1 outputted from theoperation control unit 32 of the ADC 11, line (e) indicates an executionsignal EXE_1 outputted from the operation control unit 32 of the ADC 11,line (f) indicates ready signal RED_1 outputted from the executioncontrol unit 33 of the ADC 11, line (g) indicates a trigger signal TRI_2outputted from the event management unit 31 of the ADC 12, line (h)indicates an entry signal ENT_2 outputted from the operation controlunit 32 of the ADC 12, line (i) indicates a synchronized output signalSYNCOUT_2 outputted from the operation control unit 32 of the ADC 12,line (j) indicates an execution signal EXE_2 outputted from theoperation control unit 32 of the ADC 12, and line (k) indicates a readysignal RED_2 outputted from the execution control unit 33 of the ADC 12,respectively.

When the event “0” is designated by the inputted event signal EVE, theevent management unit 31 of each of the ADC 11 and the ADC 12 changesthe synchronization instruction signal SYNC to a high level andinstructs the operation control unit 32 to execute the synchronousconversion operation. Meanwhile, as illustrated in FIG. 2, the analoginput CH_0 is assigned to the ADC 11 and the analog input CH_1 isassigned to the ADC 12 in the event “0”, respectively. Accordingly, therespective event management units 31 of the ADC 11 and the ADC 12 notifyof the existence of the event to be executed by setting the triggersignal TRI_1 and the trigger signal TRI_2 to a high level for apredetermined period, respectively.

In response to the input of the trigger signal TRI_1 and the triggersignal TRI_2, the operation control units 32 of the ADC 11 and the ADC12 request the execution control units 33 to get ready for execution ofthe AD conversion by changing the entry signal ENT_1 and the entrysignal ENT_2 to a high level, respectively.

Here, if the ADC 11 is in the state of standby without executing anotherevent, the execution control unit 33 of the ADC 11 changes the readysignal RED_1 to a high level for a predetermined period in response tothe input of the entry signal ENT_1, thereby notifying the operationcontrol unit 32 that the execution control unit 33 is ready.

After receiving the input of the ready signal RED_1, the operationcontrol unit 32 of the ADC 11 instructs the event management unit 31 andthe execution control unit 33 to execute the AD conversion by changingthe execution signal EXE to a high level in the case of an ordinaryoperation where the synchronization instruction signal SYNC is at a lowlevel. On the other hand, in the case of the synchronous conversionoperation where the synchronization instruction signal SYNC is at a highlevel, the operation control unit 32 notifies the operation control unit32 of the ADC 12 that the ADC 11 is ready for the AD conversion bychanging the synchronized output signal SYNCOUT_1 to a high level.

In the meantime, when the ADC 12 is executing another event, theexecution control unit 33 of the ADC 12 inputs the entry signal ENT_2and then notifies the operation control unit 32 that the executioncontrol unit 33 is ready by changing the ready signal RED_2 to a highlevel for a predetermined period after completion of the event inexecution.

In the synchronous conversion operation where the synchronizationinstruction signal SYNC is at a high level, the operation control unit32 of the ADC 12 having received the input of the ready signal RED_2changes the synchronized output signal SYNCOUT_2 to a high level,thereby notifying the operation control unit 32 of the ADC 11 that theADC 12 is ready for the AD conversion.

Thereafter, when both the synchronized output signal SYNCOUT_1 and thesynchronized output signal SYNCOUT_2 are changed to a high level, theoperation control unit 32 of each of the ADC 11 and the ADC 12 instructsits event management unit 31 and its execution control unit 33 toexecute the AD conversion by changing the execution signal EXE to a highlevel. Accordingly, the operation control unit 32 of the ADC 11 waitsuntil the ADC 12 is ready. Thus, the start time for the AD conversion ofthe ADC 11 and the ADC 12 is controlled at the same hour.

Although this embodiment describes the example of providing the two ADC11 and 12, this embodiment is readily applicable to a case of providingthree or more ADC as well by conducting an OR operation of thesynchronized output signals SYNCOUT outputted from all of the ADC andchanging the execution signals EXE to a high level accordingly.

Moreover, a register 40 that changes codes (channels) unique to theanalog inputs CH_0 to CH_n connected to the MPX 21 and 22 by setting maybe provided as illustrated in FIG. 5. The ADC 11 and 12 change theanalog inputs CH by designating a channel for the selection signal SEL.Accordingly, the configuration that allows the change of the uniquecodes (the cannels) by the setting of the register 40 makes it possibleto modify the correspondence of the events to the analog inputs CH_0 toCH_n without changing the connection of the analog inputs CH_0 to CH_n.

For example, in the case of an event to perform the AD conversion in theorder of analog inputs CH_a to CH_d that have channels of “00”, “01”,“10”, and “11”, respectively, the order of the AD conversion is modifiedto the order of the along inputs CH_d to CH_a by setting the register 40to transpose numerals “0” and “1” in the channels.

As described above, according to this embodiment, the AD conversiondevice 1 includes the AD converters (the ADC 11 and 12) each of whichperforms the AD conversion of an inputted analog signal into a digitalsignal, where each of the ADC 11 and 12 independently executes an eventinstructed by a host device. Here, each of the ADC 11 and 12 includes:the execution control unit 33 that controls execution of the ADconversion; the event management unit 31 that notifies of asynchronization instruction by changing the synchronization instructionsignal SYNC to a high level when the synchronous conversion operation(the event “0”) set up with the synchronous conversion operation isinstructed as the event; and the operation control unit 32 that notifiesthe counterpart ADC 12 or 11 that the ADC 11 or 12 is ready for the ADconversion by changing any of the synchronized output signal SYNCOUT_1and the synchronized output signal SYNCOUT_2 to a high level when thesynchronization instruction is notified and the execution control unit33 is confirmed ready for the AD conversion, and instructs the executioncontrol unit 33 to execute the event “0” after all of the ADC 11 and 12are confirmed ready for the AD conversion based on the changes of boththe synchronized output signal SYNCOUT_1 and the synchronized outputsignal SYNCOUT_2 to a high level.

This configuration allows each of the ADC 11 and 12 to confirm that thecounterpart ADC 12 or 11 is ready for the AD conversion by use of thesynchronized output signal SYNCOUT_1 and the synchronized output signalSYNCOUT_2. Accordingly, it is possible to perform synchronous control ofthe ADC 11 and 12 independently of the host device and without imposinga burden on the host device.

Moreover, according to this embodiment, in the state where thesynchronization instruction is not notified due to the reason that theevent is not the event “0”, and when the operation control unit 32confirms that the execution control unit 33 is ready for the ADconversion, the operation control unit 32 instructs the executioncontrol unit 33 to execute the event without notifying the counterpartADC 12 or 11 that the ADC 11 or 12 is ready for the AD conversion.

This configuration makes it possible to switch between the synchronousconversion operation and the independent operation by using thesynchronization instruction signal SYNC (the synchronizationinstruction).

Furthermore, according to this embodiment, the event “0” is set as thetop priority among all of the events. Therefore, the event managementunit 31 executes the event “0” on a priority basis when two or moreevents including the event “0” are in a standby state.

This configuration makes it possible to execute the synchronousconversion event set with the synchronous conversion operation easily ona priority basis, and thus to minimize waiting time for the synchronousconversion operation.

It is necessary to perform AD conversion of two or more analog signalsat the same hour in order to perform control calculation of a powersupply circuit. For this reason, the related art provides as many ADconverters as the analog signal inputs to be subjected to the ADconversion at the same hour. In this case, however, the host device hasto perform synchronous control of the AD converters, which is burdensometo the host device.

According to the one or more embodiments described above, each of the ADconverters can confirm that the counterpart AD converter or convertersare ready. This makes it possible to perform the synchronous control ofthe AD converters independently of the host device and without placing aburden on the host device.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only and not limitation. Numerous changes to the disclosedembodiments can be made in accordance with the disclosure herein withoutdeparting from the spirit or scope of the invention. Thus, the breadthand scope of the present invention should not be limited by any of theabove described embodiments. Rather, the scope of the invention shouldbe defined in accordance with the following claims and theirequivalents.

1. An analog-to-digital conversion device that independently executeseach of events instructed by a host device, comprising: at least twoanalog-to-digital converters that convert an inputted analog signal intoa digital signal, wherein each of the analog-to-digital convertersindependently executes an event instructed by the host device, whereineach of the analog-to-digital converters comprises: an execution controlunit that controls execution of the analog-to-digital conversion; anevent management unit that notifies of a synchronization instructionwhen a synchronous conversion event set up with a synchronous conversionoperation is instructed as the event; and an operation control unit thatmakes a notification to the analog-to-digital converters, and instructsthe execution control unit to execute the synchronous conversion event,wherein when a particular one of the analog-to-digital convertersreceives the synchronization instruction and the execution control unitof the particular analog-to-digital converter is confirmed ready for theanalog-to-digital conversion, the operation control unit in theparticular analog-to-digital converter notifies the particularanalog-to-digital converter is ready for the analog-to-digitalconversion to the analog-to-digital converter other than the particularanalog-to-digital converter, and instructs the execution control unit toexecute the synchronous conversion event after a confirmation that allof the analog-to-digital converters are ready for the analog-to-digitalconversion.
 2. The analog-to-digital conversion device of claim 1,wherein in a state where the synchronization instruction is not notifieddue to a reason that the event is not the synchronous conversion event,when the operation control unit of the particular analog-to-digitalconverter confirms that the execution control unit of the particularanalog-to-digital converter is ready for the analog-to-digitalconversion, the operation control unit instructs the execution controlunit to execute the event without notifying the other analog-to-digitalconverter that the particular analog-to-digital converter is ready forthe analog-to-digital conversion.
 3. The analog-to-digital conversiondevice of claim 1, wherein the synchronous conversion event is set as atop priority among all of the events, and the event management unitexecutes the synchronous conversion event on a priority basis whenevents including the synchronous conversion event are in a standbystate.
 4. An analog-to-digital conversion device that independentlyexecutes each of events instructed by a host device, comprising: aplurality of analog-to-digital converters comprising at least a firstand a second analog-to-digital convertors that convert an inputtedanalog signal into a digital signal, wherein each of theanalog-to-digital converters independently executes an event instructedby the host device, wherein each of the analog-to-digital converterscomprises: an execution control unit that controls execution of theanalog-to-digital conversion; an event management unit that notifies ofa synchronization instruction when a synchronous conversion event set upwith a synchronous conversion operation is instructed as the event; andan operation control unit that makes a notification to theanalog-to-digital converters, and instructs the execution control unitto execute the synchronous conversion event, wherein when the firstanalog-to-digital converters receives the synchronization instructionand the execution control unit of the first analog-to-digital converteris confirmed ready for the analog-to-digital conversion, the operationcontrol unit in the first analog-to-digital converter notifies the firstanalog-to-digital converter is ready for the analog-to-digitalconversion to at least the second analog-to-digital converter, andinstructs the execution control unit to execute the synchronousconversion event after a confirmation that the plurality ofanalog-to-digital converters are ready for the analog-to-digitalconversion.